JPH01143297A - Absorber of vhf and uhf band radio wave - Google Patents

Abstract

PURPOSE:To eliminate ghost troubles for TV radio wave almost completely, by providing a plural sets of combinations which connect main elements of VHF and UHF band radio wave antennas each other through a matching resistance in the arrangement direction of main elements and a direction crossing at a right angle thereto on a radio wave irradiation surface having properties to reflect VHF and UHF band wave. CONSTITUTION:Combinations 2-1, 2-2,... connect main elements 3-1, 3-2,... of V/U band radio wave antennas through matching resistances 4-1, 4-2,.... A plurality of sets combinations are arranged on a body 1 having properties to reflect radiated V/U bane radio wave in a direction P-P wherein main elements 3-1, 3-2,... are arranged and a direction Q-Q which crosses at a right angle thereto. When a matching resistance is connected to a main element positioned on a surface of a body whereon wave is directed, the wave directed to a certain area around the combination is received and absorbed by the resistance. Therefore, if combination of antenna and resistance are arranged at definite intervals in all directions through irradiation area, the entire irradiated surface is effective as a radio wave absorber.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is applied to objects that reflect VHF and UHF band (hereinafter abbreviated as V-tJ band) radio waves, such as skyscrapers. This invention relates to a radio wave absorber composed of a combination body terminated with a flat resistor.

[Prior Art] (1) High-rise buildings serve as significant shields and reflectors for U-band radio waves, especially radio waves for TV broadcasting. When it becomes impossible to receive TV signals in an area where radio waves are blocked by a building, the area is relatively clear, so each viewer can receive signals from a communal reception device installed outside the area where the reception point is blocked. This can be solved by wiring the cable. However, when radio waves are reflected, it is possible to receive the reflected radio waves in unexpected directions, which means that direct waves and reflected waves are received simultaneously, causing ghost interference, especially in TV radio waves, and TV reception. The image quality is significantly degraded. Ghost failure has a wide range of effects, and even if you create a joint viewing facility,
If you are tens of kilometers away from the source of the disturbance, the negative band is a ghost interference reception zone, and there is no place where you can receive good reception, making it extremely difficult to set up a joint viewing facility.

For this reason, studies have been conducted to absorb radio waves so that they are not reflected from buildings, etc. even when radio waves are irradiated. Practical examples include attaching radio wave absorbers to the walls of buildings and changing the material of the reflective surfaces themselves.

A practical example of a radio wave absorber is one that converts radio wave energy into thermal energy while the incident wave passes through the material.In the example of a product, it is a mixture of iron oxide and divalent metal (manganese, nickel) oxide. It is sintered and has a thickness of 2 to 12 m, and an absorption rate of about 99%.

Changing the material of the reflective surface means, for example, changing the metal net for ball protection at golf courses and baseball fields to nylon net.

[Problems to be Solved by the Invention] Subcommittee P Radio waves reflected by high-rise buildings cause ghost disturbances that extend to extremely distant places, and the disturbance caused by the Sunshine Building in Jibukuro extends as far as Choshi in Chiba. As a result of experiments, it was found that using a "ferrite structure" as the radio wave absorber mentioned above is quite effective, but the thickness of the absorber is about l and the weight is 45+r per rrr. Since it is expensive (250,000 to 500,000 yen for 1 meter), it has only been implemented in a few cases so far.

Although it is possible to change the material of reflective surfaces such as walls from the beginning of the design, it is difficult to do so once the construction has already been completed, and when the net is made of nylon, it has the disadvantage of being weak in strength.

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks and provide a radio wave absorber that can be easily applied to buildings after construction by combining simple materials such as those used in receiving antennas.

[Means for Solving the Problems] FIG. 1 is a diagram showing the basic configuration of the present invention. In Fig. 1, 1 is a radio wave reflector such as the surface of a building, 2-1.2
-2...- is a combination of main element and resistor, 3-1.
3-2-- is the main element of each Annana, 4-1.4-
2- indicates a matching resistance.

The present invention is constructed as follows. In other words, an object (1
) on the radio wave irradiation surface of
- a combination 2-1, 2-2- connected to each other by,
The direction P-P in which the main elements 3-L3-2... are arranged,
A plurality of sets are arranged in the direction Q-Q orthogonal thereto.

[Operation] When a matching resistor is connected to the main element placed on the surface of the object to which the radio waves are irradiated, the radio waves irradiated to the area around the combination are received and absorbed by the resistor. By arranging the antenna/resistance combinations vertically and horizontally at intervals equal to the width of the antenna and covering the entire irradiation range, the entire irradiation surface becomes effective as a radio wave absorber.

[Example] Fig. 2 is a perspective view of an example of the present invention in which two types of combinations 2-1.5-1 of a V HF band low channel and a high channel are arranged in parallel and placed on the wall of a building. In the figure, the radio waves are irradiated onto the wall from the direction of a thick white arrow 7 (the angle with the wall is θ). At this time, the main elements 3-1, 5-1 of the combination each use an A wavelength doublet, and each element is connected by a resistor 4-1.

Regarding the lengths of both ends of the two main elements 3-1 and 5-1, the length LW that correctly faces the arrow 7 needs to be λ/2. Here, λ indicates the wavelength of the radio wave. Therefore, for combination 2-1, LD (low) = (λ (long) /
2) As for the secθ combination 5-1, use one having a length expressed by the formula LI)(high)=(λ(short)/2)·secθ. Here, LD (low) is T
Low channels (long wavelength side) like channels 1 to 3 of V,
LD (high) refers to a high channel (shorter wavelength side), such as TV channels 4 to 12. Here, the main element can be an aluminum hollow pipe with a diameter of 1 cta. Also, the vertical spacing of combination 2-1.5-1 is λ (short)
/4 or less, and other combinations of the same type are arranged close to each other in the horizontal direction. Therefore, a larger number of combination bodies 5-1 are arranged in the horizontal direction.

The length of each main element 3-1 for the low channel for avoiding reception ghosts of television radio waves is about 0.75 m, and the length of the main element 6-1 for the high channel is about 0.72 m. Furthermore, the value of resistor 4-1.4-2- is approximately 75Ω.

FIG. 3 is a diagram illustrating energy absorption in one of the antenna main element and resistor combinations. The thick line is the half-wavelength doublet, and the thin solid line is (λ/2)
λ/4) rectangle. The range in which energy can be absorbed is within the range indicated by the broken line 8, and its area is approximately λ2/8.

FIG. 4 is a diagram schematically showing a plurality of combinations arranged as radio wave absorbers. In order to attach it to a building that has already been constructed, it is preferable to affix the synthetic resin film to which the assembly is attached to the wall of the building with an adhesive. In addition, when multiple TV broadcast radio waves are used as U-band radio waves, the wavelength may differ slightly from the used wavelength depending on the element length, and the radio wave absorption effect may deteriorate, but by finely adjusting the resistor and the spacing of the combination, Characteristic deterioration can be prevented.

Other possible methods include making the other elements themselves with matching resistors, or printing the elements on the wall.

Above, we have explained the half-wavelength doublet as a combination, but in addition to that, there is also a folded doublet (resistor 300
Ω), fan antenna (resistance 75Ω), other current ■・U
Various types of band antennas are applicable. Here, the fan antenna is a combination of a large number of conductive wires connected by a resistor, as shown in FIG.

In these cases, a wider range of wavelengths can be matched than in the case of a half-wavelength doublet.

Further, when the reflective surface of the building is made of metal, it is preferable to install the combination body and the building so that the capacitance between them can be ignored.

[Effects of the Invention] In this way, according to the present invention,
Since the elements used as receiving antennas for broadcast radio waves can be used as they are, the material cost is extremely low (and extremely lightweight, and can be easily installed on buildings, etc.). It is easy to install the T
Ghost interference can be almost completely eliminated for V radio waves.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle configuration of the present invention, and FIGS. 2 to 5 are diagrams showing the configuration of an embodiment of the present invention. 1- Radio wave reflecting object 2-1.2-2- Lifetime element/resistance combination 3-
L3-2-, 6-1.6-2-Issei Element 4-L4
-2-m-Resistance patent applicant Agent: Nippon Television Broadcasting Network Co., Ltd.
Patent Attorney Lead End Eikai QI 02 Figure 1 Example 2 Figure 3 Figure 11...r...'--iJ...r λ (short)/2 Figure 4 Fan Tag Zhonggyu Procedural Amendment Stamp Button 1, Incident Indication of 1986 Patent Application No. 301005 2, Name of the invention VHF and UHF electromagnetic wave absorber 3, Relationship with the case of the person making the amendment Patent applicant name Nippon Television Broadcasting Network Co., Ltd. Representative Takagi Thief 4, Agent Address: 1-13-36 Yoyogi, Shibuya-ku, Tokyo, Number of inventions to be increased by the amendment: None 7, Column 8 for detailed explanation of the invention in the specification subject to the amendment, Contents of the amendment as shown in the attached sheet Figure 5 (1) Page 7 of the specification, line 18, "And other..." to line 20, "-It is possible." shall be amended as follows. Record

Claims (1)

[Claims] On the radio wave irradiation surface of an object (1) that has the property of reflecting radio waves when VHF and UHF charged radio waves are irradiated, a VH
Main elements of F and UHF radio wave antennas (3-1
) (3-2)… Resistors (4-1) (4-2)…
Combination bodies (2-1) (2-2) connected to each other by...
A VHF and UHF band characterized in that a plurality of sets of are arranged in the direction (P-P) in which the main elements (3-1) (3-2)... are arranged and in the direction (Q-Q) perpendicular thereto. Radio wave absorber.